Thermoelectric devices comprising a plurality of thermocouples formed from a P-type thermoelement and an N-type thermoelement have long been known for producing heating or cooling. Such devices generally used a P-type semiconductor or thermoelement connected to an N-type semiconductor or thermoelement. Depending upon the direction of the current flowing across the N and P junctions, the devices may produce heating or cooling at the junction.
Many different techniques have been heretofore used to construct or fabricate such thermoelectric devices. The majority of such prior techniques have required a substantial amount of manual steps, thus creating a high cost of manufacture, as well as producing quality control problems. Moreover, such thermoelectric devices are made up of various small brittle elements which are subject to fracture or breakage under rough handling. The brittle nature of the elements creates additional problems in fabrication utilizing manual techniques, and also presents problems when the devices are utilized in hostile environments.
Numerous techniques have been heretofore developed to manufacture thermoelectric arrays. U.S. Pat. No. 2,980,746 issued to Claydon on Apr. 18, 1961, discloses the use of a jig formed in the shape of an egg box to provide a rectangular array of cells or pockets. P and N elements are disposed in the pockets in U-shaped aluminum connectors and then connected on opposite ends of the P-N type elements. The jig is then removed and the assembly is potted in a heat insulating resin. This technique still, however, required manual placing of the individual elements in making the electrical contacts and removing the jig. Therefore, this technique did not solve the problems of eliminating manual intervention while providing thermoelectric array of superior operating characteristics.
Because it is difficult to properly align and form such small N and P elements, techniques using patterns and jigs have been heretofore utilized. Such a technique is disclosed in U.S. Pat. No. 3,276,105 issued to Alais, et al., on Oct. 4, 1966. Again, however, such techniques require manual intervention with the above-described problems.
Various other techniques for forming thermoelectric devices are disclosed in U.S. Pat. No. 3,781,176 to Penn, et al., issued on Dec. 25, 1973; U.S. Pat. No. 3,780,425 issued to Penn, et al., on Dec. 25, 1973 and U.S. Pat. No. 3,560,351 issued to Abbott, et al., on Feb. 2, 1971. However, none of these prior art techniques has presented a technique for forming an array of N-P thermoelectric elements in an assembly line fashion without the requirement of substantial manual intervention in which to produce a thermoelectric array of superior operating characteristics and strength.
While such prior thermoelectric arrays have been encapsulated in insulating material, such encapsulation in certain devices has not optimized the operating characteristics of the devices. A need has arisen for a technique for encapsulating thermoelectric arrays in order to maintain the structural stability of the arrays and while protecting the arrays from exterior damage, yet providing an optimum thermal insulation within the interior of the device.